Tag: 3G video Real-time monitoring Unlimited monitoring points
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Since the water conservancy monitoring points such as the reservoir dam are distributed in a relatively wide range and are far away from the monitoring center, the traditional wired connection method is adopted, the laying cost is high, and the construction period is long, and sometimes it is hindered by the mountains and rivers. It is difficult to set up cables, so the way of wireless transmission is favored in the water industry monitoring system. The existing wireless networks mainly have the following types:
·Satellite communication: Due to the high cost, satellite communication needs to be applied in advance, and is generally only used in military or special occasions, and is not suitable for large-scale application in the water conservancy industry;
· Microwave data transmission: Before the 3G network is not officially applied, many of the water video surveillance projects use microwave data transmission technology for video transmission, which can also meet the requirements of general monitoring. However, microwave technology requires line-of-sight transmission, which has many restrictions on terrain. Only in the open prescription can get better results;
WLAN technology: WLAN can meet the requirements of real-time video transmission, and can significantly increase the coverage radius through relaying, etc., which can meet the network coverage requirements of small water conservancy facilities, but still need to be laid in medium and large water conservancy facilities. A large number of APs, the implementation and installation of the project is as difficult as the cable connection;
Carrier-based wireless network transmission technology (2G or 3G and 4G systems in small-scale applications): Carrier-based wireless network transmission mainly refers to the use of existing wireless network operator platforms for network transmission.
Under the carrier's network, there are currently many methods such as GPRS/EDGE/CDMA/3G. The actual data upload speed except the 3G mode is generally around 60-80 kbps. Under such bandwidth, the video effect is not very satisfactory. Due to the increasing popularity and maturity of 3G networks, 3G video surveillance systems have become a hotspot for water video surveillance systems. Compared with other industries, 3G video surveillance systems are more suitable for application in water conservancy industry. The main reasons are as follows:
· Water conservancy monitoring points such as reservoir dams are distributed in a wide range, and the distance from the monitoring center is far away, and it is relatively isolated. The traditional wired connection method is adopted, the laying cost is high, the construction period is long, and even often due to rivers and mountains, etc. It is difficult to erect cables due to obstacles;
·Because the water conservancy facilities are mostly in the wild and vulnerable to lightning strikes, the laying of cables, especially metal cables, should be minimized;
· Flood control is a top priority for the water conservancy department. At this time, there are many emergencies, the location of the monitoring points is uncertain, and there is an urgent need for a video surveillance solution that can be quickly deployed.
· In the flood prevention and rescue operations of the water conservancy industry, the scheduling of personnel and vehicles is the most important. In the process of dispatching, the location and real-time video of personnel and vehicles are the key information, and the mobile video surveillance of vehicles and personnel is carried out wirelessly. Achieve visual scheduling and command.
At present, the video transmission in the 3G mode can reach an upload speed of up to 700Kbps, and generally can also be in the range of 400-500Kbps, which satisfies the requirements of general real-time video surveillance. This article will give a brief introduction to the 3G video surveillance system in combination with the wireless video surveillance project example, and focus on how to better meet the application characteristics of the water industry.
Demand characteristics of water conservancy wireless video surveillance system
In addition to the general characteristics of 3G systems, the video surveillance system of the water conservancy part also has the following industry characteristics:
·The equipment must meet the requirements of field use, especially considering the requirements of waterproof, lightning protection and wind resistance;
· Support camera remote control in 3G mode, with good controllability, easy to conduct global monitoring of the command center;
·Using solar energy, wind energy and other power supply methods in the absence of on-site power supply;
· The system should reserve multiple serial and IO interfaces, so that other water monitoring systems can also upload information through the 3G system;
· The network annual usage fee should be fully communicated with 3G operators such as telecommunications. In the flood season, the traffic bandwidth will be increased to ensure better application. It is recommended to settle according to the annual traffic fee.
According to the application characteristics of the above industries, the product form suitable for the water conservancy 3G video surveillance system is shown in Table 1.
The above various types of wireless video encoders can be stored by hard disk or FLASH. For portable and car-mounted occasions, it is recommended to use FLASH for storage. Generally, 16G FLASH can meet single-channel video for more than 3 days of real-time video. data.
Introduction of 3G video surveillance system in water conservancy industry
3G video surveillance realizes the complete digitalization and network of video, enabling users to remotely monitor and centrally manage through the network anytime and anywhere, completely solving the limitation of geographical boundaries. The specific structure is shown in Figure 1. We divide the system into four parts.
Wireless monitoring point
The monitoring point is composed of a camera and a wireless encoder (including an embedded 3G module). The camera is responsible for collecting video data and encoding by the wireless encoder, and transmitting the encoded data to the command center through 3G. The part is mainly divided into mobile. There are two types of monitoring points and wireless fixed-point monitoring. Considering the integrity of the system, the existing wired monitoring points can also be connected to the wireless monitoring system.
Transmission part
Both wireless and wired transmission methods will be used in the system.
·Wireless mode: 3G mode is used for video transmission. In practical applications, it is necessary to test the local operator 3G network and select the appropriate 3G mode.
Wired mode: Wired monitoring mainly uses cable broadband to transmit video, and can lease telecom or other operators' wired networks.
Command center server
Install the corresponding server system and platform software in the command center to realize unified management of wireless monitoring points and wired monitoring points, and distribute data streams and video streams for monitoring by staff. The actual application system will include multiple servers, mainly including a management server, a recording server, a streaming media forwarding server, and several application servers, each of which provides several functions.
application
The staff operates and manages the system through the client software, obtains corresponding videos and other water-related information according to the user's authority to make decisions as soon as possible, and can also perform remote command through the system to issue instructions.
Features
3G video surveillance, in the water industry, can achieve real-time video surveillance, alarm, playback, event and background management and maps.
Real-time video surveillance
Multi-screen monitoring: The real-time video window is monitored in the form of multiple screens, supporting up to 36 screens and supporting multiple window display modes;
· Full screen display: display the real-time video window in full screen mode;
· Manual recording: manually recording the video in the current window;
· Support image capture function;
· Remote control of camera rotation and lighting, etc. It is suitable for night water monitoring and can be directly controlled on the video screen;
· You can directly access the GPS track point on the electronic map to obtain a real-time floating video monitoring window to realize the video monitoring of the sand table mode, and can be combined with the current water and rain system of water conservancy to provide real-time video to the water conservancy business system.
Alarm function
· Support burglar alarm, emergency alarm and water rain alarm (realized with water database);
· Support user confirmation function after alarm;
· When the alarm occurs, the corresponding monitoring point or vehicle on the map is highlighted, and the corresponding video is automatically connected.
Playback function
· Waterproof and anti-mite vehicles support trajectory playback, video playback and trajectory and video linkage playback when equipped with GPS;
· Support video playback drag and fast forward;
· Support the interception of part of the video download and playback;
· Provide local playback tools for a variety of video compression formats.
Events and background management
·Event query: According to different user rights, you can query the corresponding event information;
· Background management: display background management interface, background management can achieve effective management of a variety of information (such as: users, water events, permissions, etc.).
Map function
· Support MAPINFO and GOOGLEMAP maps, two maps can be switched freely in a system;
· Basic map operations such as zoom, drag and eagle eye, support for scroll wheel operation;
· Draw points, draw lines and map measurements on the map, including distance measurement and area measurement;
· Information inquiry, query various vehicle and monitoring point information;
· Monitoring point management: You can add monitoring point information and other business information.
Other functions
·Window double screen: map and video can be displayed separately;
· Device IP address display, obtain device network traffic statistics;
· Support the function of sending short messages to devices through IP mode, display on the device side screen, and the software platform records for future reference;
· Support chart function, which is accessed by the client according to the actual site environment;
· Support SMS group sending at emergency time for emergency notification and alarm;
· Supports access control devices such as RFID, and can link SMS or screenshot functions to further realize unmanned management of small water conservancy facilities.
3G video surveillance system key technology points
Equipment performance requirements
Cameras need to meet the requirements of water conservancy field applications, and have IP66 protection level; 3G video server needs to support multi-channel video simultaneous encoding, light and easy to install and has lightning protection function; should be equipped with waterproof case to further waterproof and anti-resistance Wind and other requirements.
Video transmission optimization in 3G environment
The current 3G network can basically meet the real-time transmission requirements of one-way CIF images, but the 3G network also has the problem of large fluctuations in network bandwidth and more blind spots. Therefore, if the network transmission part is not specially designed, the video effect will be unsatisfactory. In order to better carry out data transmission under the existing wireless network, the current wireless transmission part adopts the following methods to optimize in the encoder and software parts.
· Obtain the real-time bandwidth of the wireless network by analyzing the wireless connection strength and state of the 3G module, and adjust the video coding parameters and code stream control of the wireless video encoder;
· Perform appropriate error correction processing on the transmitted video data packets to adapt to the high error rate of the wireless network;
· Increase the capacity of the buffer pool, adopt the mechanism of the flow control bucket to achieve the rate balance, and ensure the smooth transmission and reception of data;
· When the 3G network is converted to 2G or instantaneous disconnection, reduce the existing code stream to below 100K, and properly refresh the video buffer to ensure real-time performance. In the 3G network recovery process, gradually increase the code stream to ensure smoothness. Video effects.
Recording call in 3G environment
In the 3G wireless environment, due to limited bandwidth, the entire video file download takes a long time. To do this, you need to confirm the event occurrence point during download and achieve accurate download to the second in the video file to speed up the download speed of the effective video. .
When the user selects a time period for video playback, the user first plays back in the low frame rate mode, and can also use the fast forward or drag mode to increase the playback speed. The user confirms the time point of the event in this mode, and then queries according to the time point. Record to a few minutes around this time point and download a clear image containing all the frames for detailed analysis.
The device supports query and video file segmentation in seconds, and supports fast-forward dragging in streaming mode.
Camera control in 3G environment
In the 3G wireless network environment, because the video transmission frame rate sometimes fails to meet the real-time requirements, and the overall delay is large, when the video is transmitted to the water conservancy remote monitoring center through the 3G network, the staff remotely controls the camera and feels less sensitive, resulting in A situation where the target point cannot be accurately located. The camera is closely integrated with the 3G video server and software. When the camera starts to rotate, it accelerates the buffering between the video to improve the sensitivity of the camera. At the same time, the target control method is adopted to better realize video surveillance.
Conclusion
The 3G video surveillance system has been initially applied in the water conservancy industry. As it can solve many problems that plague video applications in the water industry, it can be expected that the future of 3G monitoring in the water industry will be promising.
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